Polymers can be used for various biomedical and/or bioengineering applications. For example, polymers that are capable of self-assembling into thermodynamically stable micelles have become increasingly important in pharmaceutical and medical applications. In aqueous solution, micelles typically have a structure comprising a hydrophobic core or “tail” section at the interior of the micelle and a hydrophilic corona or “head” section at the exterior of the micelle in contact with the solvent. The hydrophobic core can house hydrophobic drugs, and the hydrophilic corona can function as a steric barrier to prevent micelle aggregation, ensuring micelle solubility in an aqueous environment.
In addition, fluorescent micelles have gained significant attention in recent years for so-called “theranostic” (therapeutic plus diagnostic) applications. Existing strategies to provide fluorescent properties to micelles are typically centered on conjugating or encapsulating fluorescent organic dyes (such as rhodamines, cyanines, or fluorescein), quantum dots, or gold nanoparticles on or within the micelles. However, conjugation or encapsulation of these materials often results in low fluorophore-to-micelle ratios, increased micelle size, inferior photo-bleaching resistance, and/or significant cytotoxicity. Further, premature leakage of some fluorophores into surrounding tissues can interfere with the detection of samples of interest. Therefore, there is a need for improved fluorescent micelles and improved methods of making and using fluorescent micelles.
Similarly, there is also a need for improved fluorescent polymers that may or may not form micelles. For example, some polylactones have been approved by the United States Food and Drug Administration (FDA) for use in biomedical implants such as orthopedic fixation devices and tissue grafts. In addition, synthetic polylactones can be biodegradable. However, the structure of some existing polylactones does not provide self-reporting of the degradation of biomedical implants formed from the polylactones. The resulting lack of in vivo quantitative data regarding degradation and variation in biological activity has significantly hindered the development of improved implants for use in vivo. Thus, there is a need for polymers that can enable in situ, real-time monitoring of the degradation of an implant without open surgery or animal sacrifice. Similarly, some existing polylactones do not provide theranostic capabilities. Specifically, some polylactones cannot be used for both imaging and therapeutics without the conjugation and/or encapsulation of various imaging agents by the polylactones. Such conjugation and/or encapsulation can result in dramatically increased particle size, additional cost or complexity, and/or a higher risk of adverse biological reactions to the theranostic agent.